package oj;

import java.util.Scanner;

public class Day33S {
    public static void main(String[] args) {
        long[] arr = new long[80];
        arr[0] = 1;
        arr[1] = 1;
        for (int i = 2; i < arr.length; i++) {
            arr[i] = arr[i - 1] + arr[i - 2];
        }
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int from = sc.nextInt();
            int to = sc.nextInt();
            long sum = 0;
            for (int i = from - 1; i <= to - 1; i++) {
                sum += arr[i];
            }
            System.out.println(sum);
        }
    }
}